Telegraph system



e. c. CUMMINGS. TELEGRAPH SYSTEM,

APPLICATION FILED MAY 28, 191B.

Patented Mar. 14, 1922.

/n var/far;

Gearye C. Cumm/k/yi AW" UNITED STATES" PATENT oFmefl GEORGE c. CUMMINGS, or EAST- ORANGE, NEW JERSEY, AssIGNoR' TowEsm ELEC;

TRIC COMPANY, INCORPORATED, o NEw YORK, N. Y., A CORPORATION 0 I YORK. TELEGRAPH SYSTEM.

1,499,362; Specification Letters Patent. P t tdM h 14,

Application filed May 28, 1918. Serial No. 237,010.

F igs- 2 and 3 there are shown respectively alternate arrangements for carrying out'the features of the invention, 1 e o In describing this invention, attention will :iirst bedirected to Fig. 1 of the. drawing, in which the reference character L indicates a line conductor which terminates'in 1 a duplex equipment comprising ratio arms l and 2, each bridgedby an associated condenser, an artificial line AL, transmitting dev1ces3 and 4 and receiving devices as will presently be described; In tracing the eflect of incoming message impulseswhichmay'be" assumed as'o'rigina-ting at adistant station (not shown) on the llhe L, adouble pole double throw switch 5 mayfirst be. considered as closed to its left ha'ndposition,the're= 7 by permitt ng impulsesfrom the line to- =bes Y come effective with-:a relayfi which may be of polarized type andaccordinglyresponsive in step with the polarity changes of the .in- 4" coming impulses. vThis arrangement COIIQ-x sponds with the common. .practicei'with re- I gard to the reception of telegraphicjimpulses and in describing an alternate arrangement for receiving impulses in a manner to permit the practising of the features of this-invention, the switchb may be assumed as closed in its right-hand position. Impulses from 5 thejline L may nowactv through an electro magnet l 0 to, operate, almicrophone pile '11 which may be in the form ofia' telephone transmitter button. At this-timeja second. double pole switch 13 will be'unders'tood as in .its closed position, thereby permitting feeble signaling currents as more particn- V i f reSiStflIlce ill h microphone larly employed in connection with signaling plle 11 to cause an associated battery12 to Over submarine bl C m it i it efiect current changes in the winding16 of long land lines, the present invention contransformer sp 150 Such templates the employment of neutralizing or r n s in h wi d gflfi o p n g compensating equipments to be included with rent changes are induced in thewinding 1 a regularduplex equipment in such a manner 0f hlS transformer, and Since the "a that associated telegraphing receiving devices winding is connected toformv-a clo ed 1 0p may be shielded or protected from extraneous clrcuit which includes the winding of a currents present through lack of nicetyof moving coil 21 of a recorder 20 which may, adjustmentsin the balancing of duplex cirfor convenience, be of the undulator'type, cuitg these translated impulses will bejthereby This invention is illustrated diagrammatireproduced on a record strip 22 in the wellcally in the accompanying drawing, and, for known manner. As well understood in conthe Sake of clearness, only so much of a messages 1331.105.

nection with duplex vworking, telegraphic equipment has been shown as -:be under transmission fromthekeys 3'and4 will be necessary to a clear understanding during the time incoming message impulses of the system. i y p I are under reception as described, and since,

In the drawing, Fig. 1 illustratesone emas already pointed .out, ,it is not possible-to bodiment of the present invention, while in- To all whom it may concern.

Be it known that I, GEORG C. CUMMINGS, a subject of the King of Great Britain, residing at East Orange, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Telegraph Systems, of which the following is a full, clear, concise, and exact description.

This inventionrelates to telegraph systems and moreparticularly to systems of duplex telegraphy. 1

The principal object of this invention is to provide an improved organizationof apparatus to permit a more nearly exact balancing or neutralizing effect with respect to telegraphic receiving .devices and the real and the artificial line circuits of duplex equipments. r

In seeking to employ-current amplifiers in the receptionoftelegraphic currents, ithas been foundthat the egree of balance possible with standard or commonlyemployed duplex equipments isnot sufficiently. 'accuratesince incipient line variations and slight-unbalanceof a real line with respect to an artificial line, althoughnot directly capable ofappreciably affecting associated receiving devices, may neverthelessjbecome effective through a current amplifier to cause serious difficulty in the working of duplex v systems. 7

In order to remedy this condition and thereby make it possible to secure the obvious advantages in the application of current amplifiers for. augmenting the relatively obtain, or at ,leastmaintain an absolute an artificial line24 to earth. By adjusting the capacity and resistance of the artificial line 2 it is possible to. permit just sufficient oft-he transmitted currents to pass through the transformer winding 17 as will neutra lize any extraneous or stray portions of the transmitted currents which may reach the transformer winding 16 and prevent their becoming effective with the transformer winding 18, therebyshielding the receiving device- It may be pointed out that the V stray or surge effects from the transmitted artificial line AL.

currents which may become active in the transformer winding 16, are in general, in

oppositephase -.or polarity relation with respect to .such portions of the transmitted currents as may through the transformer winding 17'. w

In'the operations of securing a balance between the real line and the artificial line ALL,

the. switch 23 may be moved to'its open po sition, while the switch-5 maybe 'inoved'to completethe circuit through ;the polar re- :lay 6, and during the time the transmitting keys 3 andd may be operated. in respectively connecting the oppositely poled sources of line battery with the neutral point of the duplex shown) included with the artificial line AL may be moved to vary the-resistance capacity and impedance of this artificia line to such point that the relay 6 will be unaffected by-the currents controlled through the keys 3 and 4. The switch 23 may remain in its open position to disconnect the derived circuit, while the switch 5 may be moved to complete the receiving circuit to the amplifier control magnet 10. The switch 13 also continues "closed at this time. ofthe, transmitting keys 3 and i may con- 7 tinue whilefurther adjustments of the artificial line devices maybe carriedfout until the least indication of interference is produced by the undulator 20'on the record 22.

The device 20 being more sensitive than. the

relay 6,-the last mentioned operations perinit in general the closest possibleadjustment between'the circuits of the line L and the At this, time the switch 23-may be closed and while the transmitting keys and 4: continue under operation the resistance and capacity of the second aitti ficial line or network 24 may be varied until the-undulator 20'is not affected and may order to prevent this effect, a derived traverse. the derived circuit equipment adjustable 1 devices (not Operation produce a relatively straight line on the record 22. Due to the adjustments dereceiving equipment at that point, while message currents from a distance station may be augmented by means of the current amplifier and thereafter rendered effective with the receiving device 20 as already describd. 7

Referring to Fig. 2 of the drawing, the arrangement shown therein differs from the one already described in that two windings 26 and 27 of a transformer 25 are connected to form the ratio arms of the duplex equipment, while the derived circuit which extends from the neutral point of this equip ment is routed through a second winding 32 of a receiving device 30. Inthe reception of signaling impulses which may originate at a distance station, such currents in traversing the winding 26 of the transform- .ei' 25 induce corresponding currents 111'21 third winding 28 of tlllStIlLllSf OFIHGI. The

switch 5 when positioned to connect the transformer winding 28 with the'i'epeater control magnet 10 permits these currents to establish amplified current effects in a circuit which includes the local battery 12 and one winding of a transformer 14; the switch 13 now in its left-hand osition; connects a second' winding of this transformer through a first winding 31 of thereceiving device 30: The relation ofthe winding 32 being differential; with respect to the winding '31 'of the undulator' 30', the network or artific-ial line 24'1I12ty be adjusted to such capacty and resistance values as will permit only sufficient current from the operation. 7 oft-he transmitters 3 and i as will be neces sarv in the winding 32 for neutralizing the effect of surge or extraneous currents which may reach the winding 31 as a result of commercial or non-exact balance of the duplex equipment of the line L and the artificial line AL. It may be pointed out that the windings 26 and 27 [are connected to form a differential effect one winding with the other 'with respect to currents transmitted from the keys. 3 and 4; therefore such currents are neutralized in the transformer 25 and thereby rendered relatively non-effective with respect to the transformer wind ing 28. For convenience of obtain ng admstments of balance in thisduplex equipmenhjfthe switch 5' may be thrown to its left-hand position while the switch 13'may be thrown to its right-hand position, thereby completing. a

closed loop circuit which includes the transformer winding 28 and the winding 31 of the undulator 30, the amplifier 10 11 being "disconnected. The switch 23 may now be opened to disconnect the derived equalizing circuit, while the keys 3 and 4 may be placed under operation and adjustments effected inthe artificial'line AL until the recorder 30 indicates the least activity and produces as nearly as possible the effect of a straight line on the record 22. The switch 23 ma now be closed andwhile operations of the keys 3 and 4 continue, the electrical characteristicsof the network 24 may be varied to such point that no effects are reproduced undulator 30. In this condition the adjustments of the duplex equipment will have been so placed that current impulsesoriginating at the home station will be rendered non-effective on the receiving device, while incoming currents may be. augmented through the amplifier andreproduced by the receiving device 30, as described. V

The alternate embodiment of this inven tion, as shown in Fig. 3 of the drawing, dif

fers from the arrangement shown in Fig. 2

in that current" amplifiers ofthe well-known thermionic type have been substituted for' the microphonic current. amplifier already."

described. For convenience, this repeater has been arranged in accordance with the socalled two-step plan. The firstrepeater 40 comprises a thermionic cathode or filament 41 which is heated by current from a source 42, an input electrode or grid '43 and an output electrode or plate 44. Theoutput electrode 44 is maintained positive with respect to the filament 41 by means of a source of direct current. In arrangements of this type, it is preferable to place an impedance 46 in series with the direct current source and to connect the true output circuit in parallel with the battery and impedance. Such output circuit usually contains a condenser 47 so that this circuit is affected only by changes in the outputcurrent.

It is well understood in connection with vacuum tube devices of this type that any change in potential difference between the electrodes 43 and 41 will cause a corresponding change in current in the out-put circuit. In describing the second-step circuit,'thermionic repeater 50 is provided with a filament 51 which is also heated by. means of the battery 42, an input grid 53 and an output plate 54. The input circuit of the repeater 50, includes a battery 55, the grid 53,

; disconnect l the derived circuit differential winding 32 of :with Fig.

the filament 5l-and an impedance unit 52,. The output or work circuit of the repeater 50 is connected to the terminals of a switch 13 and has bridged across it a battery supply circuit, including the battery 45 and the impedance 56,

be connected to the winding lator 30. It will be clear that during the time theswitches 5 and-l3 are in their righthand and left-hand positions respectively, incoming impulses from the line L as manifested through the transformer winding 28 will cause variations in the potential difference between'the grid 43 and filament 41 of the repeater 40. As commonly understood this variation of potential in the input cir-.

Variation corresponding 1n cuit will cause a kind but of increased amplitude, in the potential differences between the. grid 53 and cathode 51 of the repeater-50, and willresult in an output current through thewinding 3.1

which will have the wave nal received current but which will bes'ufiiciently. greater to cause effectiveoperation ofthe 'undulator 30.

form :ofthe. origi-. the amplitude of In arriving at a first or preliminaryadjustment balance of the duplex equipments,

the switches5-and 13 maybe placed in their 7 left-hand and right-hand, positions respec'-:'--

tively, thereby disconnecting amplifiers .40

and;50 andconnecting the transformer wind- 7 ing. 28 ina closed loop'circuit throughthe.

winding '31 ofthe; recorder. the switch 23*, should also be At this time througlr the vice 30. "Adjustments of positioned to the receiving ,.d,e;-.. V the .artificial;-.-line devices maynow be carried out in a manner similar to thatalready described-in connection.

the switches 5 and 13 maybe moved to their 2 of the drawin-g,,.following which opposite positionsto connect the amplifiers.

40 and 50 intermediate the transformer winding 28 and the undulator-30, following which further adjusting operations may be proceeded with as also described in connection with the arrangement shown in Fig. 2.

Although the thermionic type of amplifier has been illustrated in connection with the duplex equipment shown in the last two figures of the drawing,- it will be understood that this amplifier arrangement may be substituted for the microphonic amplifier system shown in connection with the bridge duplex arrangement illustrated in Fig. 1 of the drawing and that in fact any suitable type of amplifier may be used with either arrangement. It will be pointed out that instead of employing the double or two-step amplifying arrangement shown. in Fig; 3, that either a single or a multiple step arrangement may be employed in which one only or several amplifiers similar to the 70 for maintainingthe plate 54 y. positive with respect to the cathode 51. By

means of switch 13 this output circuit may 31 of the undu-i amplifiers 40 and may be 're'spectively emloyed. v Y 7 Although the embodiments'chosen for illustrating the features of this invention are considered to represent preferred arrangements, it will be understood that changes in the organization of the apparatus may be made without departing from the spirit of this invention;

What is claimed is: I W I 1. In a telegraph system, the combination of a duplex set comprising a pair of ratio arms, an artificial line, direct current transmitting means vconnected with the apex of said ratio arms, a transformer having a primary coil, means for connecting said primary coil in bridge of said ratio arms, an

alternating current receiving device associated with the secondary coil of said transformer, a leak circuit also connected with the-apex of said ratio arms and including a third coil of said transformer for rendering said receiving device non-responsive to the operation of said direct current transmitting means. i v

2. In a telegraph system, the combination of a duplex set: comprising a pair of ratio arms, an artificial linefdirect current transmitting means connected with the apex of said ratio arms, a transformer having a primary winding, means for connecting said primary winding in bridge of said ratio arms, an alternating-current receiving device associated with the secondary windingof said transformer, a leak circuit also connected with the apex-of said ratio arms and including a third winding ot A said transformer vit'or' rendering said lGCQlVlIlg ClGVlCB non-responsive to the operation of said transmitting means, and means connected in said leak circuit whereby the current flow therein may be varied.

3; A telegraph system compri conductor, a pair of ratio arms connected to said conductor, direct current transmitting means connected to the apex of said ratio sing a line arms, a transformerhaving a primary wind.-

iormer, a leak circuit also connected to the apex of said ratio arms, and means included in said leak circuit and associated with said transformer, whereby saidreceiving device is rendered non-responsive to the operation of said direct current transmitting means.

4. A telegraph system comprising a line conductor, a pair or" ratio arms connected to said conductor, direct current transmitting means connected with the apex of said ratio arms, a transformer having a primary coil, means for connecting said primary coil in bridge of said ratio arms, an alternating current receiving device connected with the secondary coil of said transformer, an amplifier interposed between said transformer and ratio arms, a leak circuit also connected to the apex of said ratio arms, and means in cluded in said leak circuit and forming a part of sald transformer for rendering said receiving device non-responsive to the operation o'fr said direct current transmitting means.

5. In a-telegraph system,the combination of a duplex'set comprising a pair of ratio arms, an artificial line, direct current transmitting means connected with the apex of said ratio arms, a transformer'having a plurality of windings, an alternating current receiving device associated with the windings of said transformer, alea'k circuit di-' rectly and conductivelyiconnected with the apex ofsaid'ratio arms, and including a winding of said: transformer for rendering said receiving device non-responsive to the 50 ed with the secondary winding of said trans- 1 operation of the directcurrent transmittting means. 7 V e In witness whereof, I hereunto subscribe my name this 23rd day of May, A. D. 1918.

onoaen o. CUMMINGS. 

